Saving of $2.10 is made by buying fleece vest on sale.
Solution:
Given that regular price of fleece vest = $15.99
And sale price of fleece vest = $13.99
Sales tax = 5%
Fleece vests regularly priced at $15.99, If sales tax is 5% then:
Regular price + sales tax = R = 15.99 + 5 % of 15.99

Fleece vests are on sale for 13.99$ , then:
Discounted Price + sales tax = S = 13.99 + 5 % of 13.99

Saving made = R - S

Thus we can save $ 2.10 by buying vests on sale